Ionization flow detector
Apparatus and method for neutralizing static charges in sheet/web feeding devices
Grounded grid static discharge apparatus
Corona charging element
Ion imbalance monitoring device
ApplicationNo. 10459865 filed on 06/11/2003
US Classes:361/213, By charged gas irradiation430/31, ELECTRIC OR MAGNETIC IMAGERY, E.G., XEROGRAPHY, ELECTROGRAPHY, MAGNETOGRAPHY, ETC., PROCESS, COMPOSITION, OR PRODUCT250/326, Charging of objects324/459, USING IONIZATION EFFECTS250/324, CORONA IRRADIATION73/861.09, Ionization type361/229, By charged gas irradiation361/231, Modification of environmental electric charge427/569, Plasma (e.g., corona, glow discharge, cold plasma, etc.)399/172, Having case250/325, Charging of moving object423/239.1, Utilizing solid sorbent, catalyst, or reactant361/227, For spray production118/620, WITH MEANS TO APPLY ELECTRICAL AND/OR RADIANT ENERGY TO WORK AND/OR COATING MATERIAL399/171Having grid
ExaminersPrimary: Sherry, Michael J.
Assistant: Nguen, Danny
Attorney, Agent or Firm
International ClassH01H 47/00
FIELDOF THE INVENTION
This invention relates to ion generators and more particularly to static neutralizing apparatus for efficiently delivering ions in a flowing stream of air or other gas.
BACKGROUND OF THE INVENTION
Electrode structure for generating ions of one or other polarity commonly rely upon a point emitter to establish an intense electrical field about the point sufficient to form ions in response to an applied ionizing voltage. However, ionsgenerated in this manner for delivery within a flowing stream of air or other gas are significantly immobilized by the intense electrical field and may be poorly delivered into the flowing stream.
Long, thin wire electrodes are known for generating ionizing electric fields over linear dimensions, for example, for delivering ions of one polarity to a closely-spaced charging object such as an imaging drum of an xerographic printing device. However, an ionizing electrode of this type is usually mounted very close to the charging object and in tension over the span of its length to assure reasonably accurate spacing between the wire electrode and imaging drum.
SUMMARY OF THE INVENTION
In accordance with one embodiment of the present invention, a non-conductive support member retains a thin ion-emitting wire electrode in proximity to a low voltage electrode, all disposed within a flowing air stream. Various configurations ofsupport member are configured to minimize air-flow restrictions in order to improve the efficiency of ion delivery from the ion-emitting wire electrode to the flowing air stream.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a plan view of one embodiment of the apparatus according to the present invention;
FIG. 1B is a sectional view of a coated electrode wire in accordance with the present invention;
FIG. 2 is a multiple-electrode configuration of the apparatus of FIG. 1;
FIG. 3 is a plan view of another embodiment of thin-wire electrodes according to the present invention;
FIG. 4 is a plan view of another embodiment of a thin-wire electrode according to the present invention.
FIG. 5 is a pictorial illustration of one electrode structure within an air-flow delivery system;
FIG. 6 is a pictorial illustration of another embodiment of an electrode structure within an air-flow delivery system according to the present invention;
FIG. 7 is a pictorial illustration of another embodiment of an electrode structure within an air-flow delivery system according to the present invention;
FIG. 8 is a pictorial illustration of another embodiment of an electrode structure within an air-flow delivery system according to the present invention;
FIG. 9 is a pictorial sectional view of a delivery system for gas under pressure including an electrode structure according to the present invention; and
FIG. 10 is a plan view of an electrode structure according to the present invention for fabrication within a confined slot in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1A, there is shown a plan view of one embodiment of the present invention in which a generally U-shaped support member 4 is formed of non-conductive electrically-insulating resilient material such as printed-circuitsubstrate, or polycarbonate, or the like. Conductive pads 2 are disposed at upper ends of the U-shaped support member and a low voltage electrode 3 is also disposed in the root or base of the U-shaped support member 4. A thin wire 1 forms ahigh-voltage emitter electrode in the span between the upper ends of the support member 4. In this configuration, the wire electrode 1 may be attached as by soldering, welding, crimping, riveting, or the like to the conductive pads 2 while the supportmember 4 is slightly flexed inwardly to retain the wire electrode 1 in tension upon return of the support member 4 toward its relaxed shape. The low voltage electrode 3 and the high voltage electrode 1 are thus configured to reside in substantially thesame plane, for mounting and connections into electrical circuits 21, as later described herein. The distance between the low and high voltage electrodes 1, 3 may be in the range of about 0.4 to about 0.8 inches, and preferably in the range of about0.5-0.6 inches for operation of the high voltage wire electrode at voltages in the range from about 3KV to about 10KV. The spacing can be optimized for the associated operating conditions of voltage (and frequency of AC ionizing voltage) and air-flowvelocity over the structure. In addition, the thickness and elastic properties of the support member 4 should be greater than such properties of the wire electrode 1. Specifically, the thickness of the support member 4 should be about 10-20 timesgreater, and preferably 10-12 times greater than the diameter of the wire electrode 1 to provide desirable aerodynamic properties to the structure, for reasons as later described herein. In addition, the Young's modulus of elasticity of the supportmember 4 should be significantly greater than the Young's modulus of elasticity of the wire electrode 1 to assure reliable tensioning of the wire electrode 1 on the support member 4 over time and temperature of operating conditions.
Referring to the sectional view of FIG. 1B, there is shown an insulating coating 5 such as glass or ceramic overlaying the electrode wire 1 for use in ultra-clean environments in which corona discharge and associated electroerosion of particlesfrom the wire electrode 1 is unacceptable. In this configuration, the electrode wire is operable on high ionizing AC applied voltage in the range of about 3KV-10KV (rms) at a frequency of about 50-100,000 Hz.
Referring now to FIG. 2, there is shown a top view of another embodiment of the present invention in which the support member 4 includes a pair of substantially U-shaped supports disposed in back-to-back configuration substantially as an H-shapedsupport member 4. The extreme ends of the H-shaped uprights each includes a conductive pad 2 that supports and connects to a tensioned, thin electrode wire 1, in the manner as previously described herein. In addition, the root or lateral segment of theH-shaped support member includes a low voltage electrode 3 disposed intermediate the high-voltage emitter electrode wires 1.
Referring now to FIGS. 3 and 4, there are shown alternative configurations of the wire electrodes 1 according to the present invention in which the electrode 1 is disposed in a loop attached to a conductive pad 2. In the embodiment of FIG. 3,the loops may be closely spaced apart from each other to establish interactive electrical fields therebetween. Similarly, in the embodiment of FIG. 4, a loop electrode 1 is disposed closely adjacent a planar electrode 3 to establish interactiveelectrical-fields therebetween. Alternatively, each of the individual loops may be associated with a helical winding of a wire electrode having a longitudinal axis disposed substantially normal to the page for delivering ions to a stream 8 of airflowing over the structure. The loop radius may be in the range of about 0.05'' to 2'', and preferably in the range of about 0.1'' to 0.5''. The diameter of the wire forming the loop electrode may be in the range from about 2 to 5 mils, and preferablyin about 2.4 to 2.5 mils.
Referring now to FIG. 5, there is shown a pictorial sectional view of apparatus for delivering ions in a flowing stream 8 of air in accordance with the present invention. A fan 15 moves a stream 8 of air within a surrounding insulative shroud 6past an electrode structure, for example, as illustrated and described herein with reference to FIG. 2. The delivery of ions into the flowing air stream 8 is dependent upon the electrode positions relative to the flowing air stream 8. Ideally, theratio of ion-generating area to area obstructing air flow past the electrodes is greater for wire electrode than for emitter point electrode. Air flow is very efficient at moving ions when they are not tightly bound by the electrical field. Theelectrostatic field intensity is at a maximum at the surface of the wire electrode 1, where all ions are created. A minimum field intensity occurs on the surface of the low voltage electrode 3. In a strong electrical field, ions are not free to followthe air flow. For that reason, the electrode arrangements according to the present invention are positioned so that the low-voltage electrode 3 is located upstream and the high-voltage wire electrode 1 is located downstream in the air flow, as shown inFIG. 8, to maximize the ion harvest into the air flow 8.
In some applications, the air flow is not uniform. In that case, it is possible to maximize ion harvest by utilizing aerodynamic forces to move the ions most efficiently. In order to accomplish this, the ionizer should have the maximum airflowat the flat low voltage electrode, typically realized near the periphery of an axial fan within a confining shroud 6.
It has been determined that optimum delivery of generated ions into air stream 8 from wire electrode 1 occurs where the ion stream flows perpendicular to, or in opposite direction to, air flow. Thus, as illustrated in FIG. 5, an H-shapedstructure as shown in FIG. 2 is disposed perpendicular to the air flow 8 and orients the low-voltage electrode 3 and the high-voltage, ion-emitting thin-wire electrodes 1 across the air flow. This establishes ion streams 7 flowing normal to the air flow8 established by the fan 15 that is positioned downstream of the ion-generating structure. In this configuration, the fan should ideally be formed of non-conductive material, or include non-conductive surface coating on conductive fan components. Alternatively, as illustrated in FIG. 6, the fan 15 may be disposed upstream of the ion-generating structure including an H-shaped support member 4, as illustrated in FIG. 2.
Referring now to FIGS. 7 and 8, there are shown other embodiments in which the ion-generating structures including U-shaped support members 4, as illustrated in FIG. 1, are oriented within a flowing air stream 8 to form an ion stream 7 inopposite direction to the air flow stream 8. In these embodiments, the fan 15 may be disposed either upstream of the ion-generating structure, as illustrated in FIG. 7, or downstream of the ion-generating structure, as illustrated in FIG. 8.
Referring now to the sectional view of an elongated corona-generating structure as illustrated in FIG. 9, there is shown a housing 14 including an upper chamber for containing electrical components, and a lower chamber 10 for containing air (orother gas) under pressure. A lower shroud 17 of electrically non-conductive material forms a shield about the ion-generating structure including low voltage electrode 3 and high voltage wire electrode 3 (shown with a coating 5, as illustrated anddescribed with reference to FIG. 1B) on support member 4 in a configuration as illustrated in FIG. 1A. This ion-generating structure produces an ion stream 7 flowing in a direction opposite to the direction of air (or other gas) flowing 8 under pressurefrom chamber 10 through aperture 11. These oppositely-directed flows of the ion stream 7 and air stream 8 are found to promote more efficient delivery of the generated ions into the air stream 8 away from the influence of associated electrical fields.
In operation, the wire electrode 1 in each of the illustrated embodiments is connected to receive a high ionizing voltage of either polarity or of alternating polarity from an associated power supply 21. The low-voltage electrode 3 may beconnected to a reference potential 23 such as ground, or may be connected as a balance-sensing electrode in a circuit 25 of conventional design for controlling in known manner at least one or other of the polarized voltages to alter the quantities ofions of one or other polarity delivered within the air stream 8. Of course, a wire electrode 1 may be alternately switched between sources of high ionizing voltages of opposite polarities, or may be pulsed intermittently with DC of one polarity, or maybe connected (e.g., capacitively) to an AC source of high ionizing voltage or directly connected to a DC source of high ionizing voltage of one polarity.
Referring now to FIG. 10, there is shown one embodiment of an ion-generating structure according to the present invention for fabrication within a slot or elongated recess 18 within a fixture 12. In this embodiment, a resilient, flexible supportmember 4 includes conductive end pieces 2 to which the wire electrode 1 is attached while the support member 4 is flexed by spacers 13 positioned between the support member 4 and walls of the groove in fixture 12. After firmly attaching the wireelectrode 1 to the end pieces 2, the spacers 13 may be removed. The support member 4 resiliently returns toward its normal shape, thereby tensioning the wire electrode 1 in a composite structure suitable for operation in the manner as illustrated anddescribed herein. Such fabricated structure may be mounted and distributed for operation and replacement in a larger structure as a disposable cartridge. As illustrated and described herein circuitry connected to the non-wire electrode 3 may be eithera source of reference potential such as ground, or a source of low voltage, or a circuit 25 for sensing ions in the vicinity of such electrode in order to control one or more sources of high ionizing voltage in known manner to achieve a selected balanceor unbalanced condition of ions flowing in an air stream 8.
Therefore, the ion-generating structures in accordance with the present invention establish ion streams that can be oriented in directions normal to, or in opposition to, the directions of flowing streams of air or other gas. This promotes moreeffective delivery of generated ions within the flowing stream.
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Field of SearchAircraft
DISCHARGING OR PREVENTING ACCUMULATION OF ELECTRIC CHARGE (E.G., STATIC ELECTRICITY)
Specific conduction means or dissipator
Structurally combined with building or vehicle
With external structure of vehicle
Of paper or paper handling machine
Chain-type grounding means
By charged gas irradiation
Of storage or hazardous area or fluid handling